JP2023159064A - Chamber surface and in-situ optical sensor in processing - Google Patents

Abstract

To provide a system and a method, for realizing an in-situ (current site) optical sensor in order to monitor a chamber surface state and a chamber processing parameter.SOLUTION: In a processing tool 100, an optical sensor 120 includes: a housing (a first housing 124 and a second housing 122); and a light path through each housing. The light path includes a first end part and a second end part, in which a reflector 121 is positioned at the first end part of the light path, and a lens 125 is positioned between the reflector and the second end part of the light path. The first housing 124 extends through an open part of a chamber 105 and extends into the chamber interior space, and an extension part such as a pipe 126 passes through the open part of the chamber 105. One or more open parts 123 are arranged along a long direction of the pipe 126, and allow an entry of an electromagnetic emission from the plasma 107 into the optical sensor 120.SELECTED DRAWING: Figure 1

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Nonprovisional Application No. 16/378,271, filed April 8, 2019, the entire contents of which are incorporated herein by reference. It will be done.

Embodiments relate to the field of semiconductor manufacturing, and more particularly to systems and methods for providing in-situ optical sensors for monitoring chamber surface conditions and chamber processing parameters.

Changes in the chamber surfaces affect various processing parameters. For example, redeposition of etch byproducts on the chamber walls can change the etch rate of a given process. Therefore, as substrates are being processed within the chamber, the etch rate (or other process parameters) may vary, resulting in non-uniform processing from substrate to substrate.

In an attempt to account for changes in processing conditions, optical emission spectroscopy (OES) has been performed within processing chambers. OES involves monitoring the emission spectrum of the plasma within the chamber. A window is placed along the chamber wall, and the emission spectrum can follow an optical path through the window to a sensor outside the chamber. When the spectrum of the plasma is changing, a qualitative analysis of the process can be inferred. In particular, OES helps determine when the endpoint of a processing step is reached. To provide the best measurements, the windows are designed to prevent deposition from occurring along the optical path. Additionally, while endpoint analysis is possible, there is currently no process for performing quantitative analysis using existing OES systems.

Embodiments disclosed herein include optical sensor systems and methods of using such systems. In one embodiment, an optical sensor system includes a housing and an optical path through the housing. In one embodiment, the optical path includes a first end and a second end. In one embodiment, a reflector is at a first end of the optical path and a lens is between the reflector and a second end of the optical path. In one embodiment, the optical sensor further includes an opening through the housing between the lens and the reflector.

In one embodiment, a method for measuring process conditions or chamber conditions within a processing chamber using an optical sensor includes obtaining a reference signal. In one embodiment, obtaining the reference signal comprises emitting electromagnetic radiation from a source outside the chamber, the electromagnetic radiation propagating along an optical path between the source and a reflector within the chamber. , reflecting the electromagnetic radiation along the optical path using a reflector, and sensing the reflected electromagnetic radiation using a sensor optically coupled to the optical path. In one embodiment, the method further includes obtaining a process signal, wherein obtaining the process signal includes sensing, using a sensor, electromagnetic radiation emitted within the processing chamber that travels along the optical path. Including. In one embodiment, the method further includes comparing the process signal to a reference signal.

In one embodiment, an optical sensing array for a plasma processing chamber includes a plurality of optical sensing systems oriented around the processing chamber. In one embodiment, each of the plurality of optical sensing systems includes a housing, a light path through the housing, the light path including a first end and a second end, and a reflector at the first end of the light path. , a lens between the reflector and the second end of the optical path, and an opening through the housing between the lens and the reflector.

FIG. 3 is a cross-sectional view of a chamber with an optical sensor penetrating a wall of the chamber, according to one embodiment. FIG. 3 is a cross-sectional view of a perspective view of a sensor housing, according to one embodiment. 2 is a cross-sectional view of an optical sensor penetrating a chamber wall and illustrating an optical path through a sensor housing, according to one embodiment; FIG. 3 is a cross-sectional view of an optical sensor after a layer of material has been deposited on a reflector, according to one embodiment. FIG. 1 is a cross-sectional view of an optical sensor with a source and sensor integrated into a sensor housing, according to one embodiment. FIG. FIG. 2 is a cross-sectional view of an optical sensor with a filter along the optical path, according to one embodiment. 1 is a top view of a processing chamber with an array of optical sensors extending through a chamber wall, according to one embodiment. FIG. FIG. 2 is a process flow diagram illustrating a process for using optical sensors to determine wall or process conditions, according to one embodiment. FIG. 2 is a process flow diagram illustrating a process for obtaining a reference signal, according to one embodiment. 1 illustrates a block diagram of an exemplary computer system that may be used in conjunction with an optical sensor having an optical path through a chamber wall, according to one embodiment. FIG.

The systems and methods described herein include optical sensors for in situ monitoring of chamber conditions and/or process conditions within a chamber. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. It will be obvious to those skilled in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects have not been described in detail in order not to unnecessarily obscure the embodiments. Furthermore, it is to be understood that the various embodiments illustrated in the accompanying drawings are exemplary representations and are not necessarily drawn to scale.

As mentioned above, currently available optical emission spectroscopy (OES) systems can provide qualitative measurements to achieve functions such as endpoint determination, but are currently unable to provide accurate quantitative measurements. . Processing parameters such as etch rate cannot be measured directly with existing OES systems. Accordingly, embodiments disclosed herein include an optical sensor system that includes an optical path through which both a reference signal and a plasma emission spectrum pass. For example, a light path begins at a light source, passes through a chamber wall, reflects off a reflector surface within the chamber, and returns toward a sensor along the light path. Since the reference signal and the emission spectrum travel along the same optical path, the reference signal can be used to determine losses due to the optical path without opening the chamber and interrupting operation. This allows accurate and quantitative measurement of the emission spectrum. Therefore, the calibrated plasma emission spectrum can be used to determine process parameters such as etch rate.

Furthermore, while currently available OES systems are designed to prevent deposition along the optical path, the embodiments disclosed herein include a reflector surface that is exposed to the processing environment. In some embodiments, the reflector surface may be selected to substantially match the interior surface of the chamber. Therefore, the deposition on the reflector surface is substantially similar to the deposition found on the inner surface of the chamber. As the reflector surface interacts with the electromagnetic radiation emitted by the source, it can be used to determine the properties of the deposited film or the transformation of the wall material. For example, the absorption of a portion of the spectrum of electromagnetic radiation may be correlated to a particular material composition and/or film thickness.

Accordingly, embodiments disclosed herein enable quantitative in-situ measurements of process conditions and/or chamber conditions. As quantitative measurements are provided by embodiments disclosed herein, embodiments may enable chamber matching measurements (i.e., comparison of a single process performed within different chambers). In some embodiments, a single optical sensor may be included within the processing chamber. Other embodiments may include an array of optical sensors positioned around the processing chamber. Such embodiments may allow chamber uniformity data (eg, plasma uniformity, chamber surface uniformity, etc.) to be obtained. Additionally, such embodiments may also provide an indication of chamber abnormalities (eg, chamber drift).

Referring now to FIG. 1, a cross-sectional view of a processing tool 100 is shown, according to one embodiment. In one embodiment, processing tool 100 includes chamber 105. For example, chamber 105 may be suitable for low pressure processing steps. In one embodiment, the processing step may include generating plasma 107 within chamber 105. In one embodiment, a substrate support 108 is within chamber 105. Substrate support 108 can be a chuck (eg, an electrostatic chuck, a vacuum chuck, etc.) or any other suitable support on which one or more substrates can be placed during processing.

In one embodiment, processing tool 100 may include an in-situ optical sensor 120. An in-situ optical sensor 120 extends through the surface of the chamber 105, with a first portion of the optical sensor 120 being inside the chamber 105 and a second portion of the optical sensor being outside the chamber 105. In one embodiment, optical sensor 120 is shown extending through a sidewall of chamber 105. However, it should be understood that optical sensor 120 may be placed through any surface of chamber 105.

In the illustrated embodiment, a single optical sensor 120 is shown. However, it should be understood that embodiments are not limited to such configurations and more than one optical sensor 120 may be included in processing tool 100. Additionally, optical sensor 120 requires only a single optical aperture (i.e., window) through chamber 105. As explained in more detail below, the optical path includes a reflector 121 that reflects electromagnetic radiation from the source 137 back through the same aperture. This is in contrast to existing systems that require an optical path across the interior space of chamber 105 and require at least two optical apertures through the chamber.

In one embodiment, optical sensor 120 includes a housing. In one embodiment, the housing may include a first housing 124 and a second housing 122. In one embodiment, first housing 124 may be secured to second housing 122 with any suitable fasteners. In other embodiments, the housing may be a unitary structure. That is, first housing 124 and second housing 122 can be combined into a single structure. Additionally, while first housing 124 and second housing 122 are disclosed, it should be understood that the housing may include any number of components coupled together.

In one embodiment, first housing 124 can extend through the opening of chamber 105 and into the chamber interior space. For example, an extension, such as tube 126, can pass through an opening in chamber 105. In one embodiment, tube 126 may be an optically transparent material. For example, tube 126 may be quartz. However, it should be understood that tube 126 need not be optically transparent. In some embodiments, tube 126 may be a ceramic or metallic material. Additionally, although tube 126 is described, it should be understood that any elongate member may extend within the interior space of chamber 105. In particular, any structure capable of supporting reflector 121 within the interior space of chamber 105 can be used.

In one embodiment, one or more openings 123 may be positioned along the length of tube 126. One or more openings 123 allow electromagnetic radiation from plasma 107 to enter optical sensor 120. Additionally, opening 123 exposes reflector 121 to the processing environment. Exposure of reflector 121 to the processing environment allows the surface of reflector 121 to be modified in substantially the same manner as the interior surfaces of the chamber are modified during the processing process. For example, byproducts deposited on the interior surface of chamber 105 may also be deposited on reflector 121. In certain embodiments, reflector 121 may include the same material as the interior surface of chamber 105. Therefore, it can be assumed that changes in the surface of reflector 121 substantially match changes in the inner surface of chamber 105. In this manner, chamber surface monitoring may be performed by optical sensor 120.

In some embodiments, reflector 121 may be a replaceable component. That is, reflector 121 may be a removable component from first housing 124. For example, reflector 121 may be attached to a lid covering the end of tube 126. The use of a removable reflector allows the reflector 121 to be replaced after its usable life. Additionally, different reflector materials can be used to match the interior surfaces of the chambers of various processing tools.

In some embodiments, a lens 125 may be secured between first housing 124 and second housing 122. A lens 125 is positioned along the optical path between source 137 and reflector 121 to focus electromagnetic radiation traveling along the optical path. In some embodiments, lens 125 may be part of a seal that closes the opening through chamber 105. For example, an O-ring or the like may be placed on the surface of lens 125 facing chamber 105.

In one embodiment, optical sensor 120 may further include source 137 and sensor 138. Source 137 and sensor 138 may be optically coupled in the optical path. For example, a fiber optic cable 132 can extend from second housing 122. In one embodiment, fiber optic cable 132 may include a splitter 134 that branches into fiber optic cable 135 to source 137 and fiber optic cable 136 to sensor 138.

In one embodiment, source 137 may be any suitable source for propagating electromagnetic radiation along an optical path. In particular, embodiments include a high precision source 137. High precision source 137 provides a known electromagnetic spectrum that can be used as a reference baseline for making measurements using optical sensor 120. In one embodiment, source 137 may be a single wavelength source. For example, source 137 can be a laser or a light emitting diode (LED). In other embodiments, source 137 may be a broadband light source. For example, source 137 can be an arc flash lamp (eg, a xenon flash lamp).

In one embodiment, sensor 138 may be any suitable sensor for detecting electromagnetic radiation. In one embodiment, sensor 138 may include a spectrometer. For example, a spectrometer may have a charge coupled device (CCD) array. In other embodiments, sensor 138 may include a photodiode that is sensitive to specific wavelengths of electromagnetic radiation.

Referring now to FIG. 2, a cross-sectional view of a three-dimensional view of the housing of an optical sensor 220 is shown, according to one embodiment. As shown, an optical path 228 extends through the housing. For example, optical path 228 extends along a channel in second housing 222 , through lens 225 , through tube 226 in first housing 224 , and toward reflector 221 . In one embodiment, an opening 223 through tube 226 allows electromagnetic radiation from the processing environment (eg, from a plasma) to enter the housing and propagate along optical path 228. Opening 223 also exposes reflector 221 to the processing environment within the chamber. Accordingly, deposition or other transformations on the surface of reflector 221 can be monitored to determine changes in the interior surface of the chamber.

As shown in FIG. 2, reflector 221 is a cap mounted over the end of tube 226. Therefore, reflector 221 can be replaced by removing the cap and installing a second cap with second reflector 221. Additionally, FIG. 2 shows a channel 227 in close proximity to lens 225. FIG. In one embodiment, channel 227 can be sized to receive an O-ring (not shown) positioned relative to first housing 224 and lens 225. Thus, even if there are openings through the walls of the chamber, a vacuum seal can be maintained.

As discussed above with respect to FIG. 1, the housing of optical sensor 220 may alternatively include a single component or more than two components (i.e., more than first housing 224 and second housing 222). It can be composed of Additionally, tube 226 can be replaced with any elongate structure capable of supporting a reflector along optical path 228. For example, tube 226 can be replaced with one or more beams extending from first housing 224.

3A and 3B, a pair of cross-sectional views illustrate a process for using an optical sensor, according to one embodiment.

Referring now to FIG. 3A, a cross-sectional view of the substrate at the beginning of processing is shown. As shown, optical sensor 320 is substantially similar to optical sensors 120 and 220 described above. For example, a housing is shown that includes a first housing 324, a second housing 322, a lens 325, and a reflector 321. Reflector 321 is shown floating in FIG. 3A. That is, only the opening 323 of the support structure is shown. However, it should be understood that the reflector 321 is connected to the first housing 324 in a structure outside the plane of the cross-sectional view. For example, one or more beams or tubes can be used to connect reflector 321 to first housing 324.

In one embodiment, reference signal 341 may be generated by a source (not shown) and optically coupled to an optical path through housings 324, 322. For example, reference signal 341 can propagate along fiber optic cable 332 before entering housing 322. Reference signal 341 can then propagate toward reflector 321 and be reflected back along the optical path as reflected signal 342. Reflected signal 342 may be optically coupled with fiber optic cable 332 and sent to a sensor (not shown).

Since the source emits electromagnetic radiation of known spectrum and intensity, the measurement of the reflected signal 342 by the sensor provides a baseline of loss along the optical path. That is, the difference between the measured value (eg, spectrum and intensity) of the reflected signal 342 and the known spectrum and intensity of the source provides a measure of the loss inherent in the optical sensor 320. Therefore, the known loss can be used to calibrate the subsequently obtained signal.

In particular, electromagnetic radiation emitted by the plasma can also be sensed by the sensor. For example, plasma signal 343 can pass through aperture 323 of optical sensor 320 and propagate along an optical path to a sensor (not shown). The plasma signal 343 measurement can then be corrected by adding back the known losses inherent in the optical sensor. A quantitative measurement of the electromagnetic radiation emitted by the plasma can thus be provided.

Referring now to FIG. 3B, a cross-sectional view of optical sensor 320 is shown after membrane 306 is disposed on the surface of chamber 305 and on the surface of reflector 321, according to one embodiment. In one embodiment, membrane 306 may be a byproduct of a processing step performed within chamber 305. For example, film 306 may be a redeposition of a byproduct of an etching process. In embodiments where the surface of reflector 321 is the same material as the interior surface of chamber 305, membrane 306 on reflector 321 will be representative of membrane 306 on the interior surface of chamber 305.

Accordingly, optical sensor 320 may also be used to determine one or more properties of membrane 306. In one embodiment, the reflected signal 342 can be measured to find differences relative to the reference signal 341. For example, a reduction in a particular wavelength of reflected signal 342 (compared to a reference signal) can be used to determine what material has been deposited on the film. In particular, certain materials will preferentially absorb portions of the spectrum of reference signal 341. Therefore, by identifying the portions of reflected signal 342 that have decreased intensity, it is possible to determine the composition of film 306. Additionally, changes in reflected signal 342 may also identify film thickness.

Referring now to FIG. 4A, a cross-sectional view of an optical sensor 420 through the surface of chamber 405 is shown, according to an additional embodiment. Optical sensor 420 of FIG. 4A is substantially similar to optical sensor 320 of FIG. 3A, except that source 437 and sensor 438 are integrated directly into second housing 422. For example, reference signal 441 may pass through prism 439 and lens 425 toward reflector 421 , and reflected signal 442 and plasma signal 443 may be redirected by prism 439 toward sensor 438 . Therefore, optical coupling of source 437 and sensor 438 to the optical path can be performed without fiber optic cables. Such embodiments may also provide a more compact optical sensor 420.

Referring now to FIG. 4B, a cross-sectional view of an optical sensor 420 through the surface of chamber 405 is shown, according to an additional embodiment. Optical sensor 420 of FIG. 4B is substantially similar to optical sensor 320 of FIG. 3A, except that a filter 445 is disposed along the optical path. In one embodiment, filter 445 can provide a specific passband to improve the signal-to-noise ratio and improve the performance of the optical sensor. In one embodiment, filter 445 is placed between lens 425 and a sensor (not shown). That is, filter 445 is placed outside the chamber interior space to be protected from the processing environment.

Referring now to FIG. 5, a cross-sectional top view of a processing tool 500 is shown, according to one embodiment. In one embodiment, processing tool 500 may include chamber 505. A substrate support 508 (eg, a chuck, etc.) may be disposed within the chamber 505. In one embodiment, a plurality of optical sensors 520 _AE are arranged in an array around the chamber 505. Optical sensors 520 _AE can be substantially similar to one or more of the optical sensors described above. In the illustrated embodiment, five optical sensors 520 _AE are shown. However, it should be understood that any number of optical sensors 520 may be included in processing tool 500. The use of multiple optical sensors 520 allows uniformity data to be obtained. For example, plasma uniformity and/or wall state uniformity may be obtained. Additionally, chamber drift may also be determined.

6A and 6B, a process flow diagram illustrating a process for using optical sensors to provide quantitative measurements in situ is shown, according to one embodiment.

Referring now to FIG. 6A, process 660 begins at step 661, which includes obtaining a reference signal that is propagated along an optical path between a reflector within the chamber and a sensor outside the chamber. In particular, step 661 may include process 670 shown in FIG. 6B.

Referring now to FIG. 6B, process 670 may begin with step 671, which includes emitting electromagnetic radiation from a source outside the chamber. In one embodiment, electromagnetic radiation is propagated along an optical path between a source and a reflector within the chamber. Next, process 670 can continue to step 672, which includes reflecting the electromagnetic radiation back along the optical path using a reflector. Process 670 can then continue to step 673, which includes sensing the reflected electromagnetic radiation with a sensor optically coupled to the optical path.

Returning to FIG. 6A, process 660 can then continue to step 662, which includes obtaining a process signal by sensing electromagnetic radiation emitted within the processing chamber and propagated along the optical path. In one embodiment, process 660 can then continue to step 663, which includes comparing the process signal to a reference signal.

In one embodiment, a comparison of the reference signal and the process signal may provide a quantitative measurement of the process signal. In particular, the reference signal may provide a measure of the losses inherent in the optical sensor. Therefore, losses inherent in the optical sensor can be added back to the process signal to provide a quantitative value of the process signal. By obtaining quantitative values, the processing status inside the chamber can be understood more accurately. Furthermore, quantitative values are comparable between different chambers. Therefore, chamber matching can be performed to improve process uniformity between different chambers.

It should be understood that the process steps disclosed in FIGS. 6A and 6B do not need to be performed in any particular order. That is, each signal can be acquired at any time. For example, in one embodiment, the reference signal may be obtained when no process is being performed in the chamber. This provides a reference signal that is unaltered by electromagnetic radiation emitted by the plasma. However, it should be understood that in some embodiments, the reference signal may be obtained while a plasma is being generated within the chamber. In other embodiments, the process signal may be acquired when the source is off. In such embodiments, a pure signal from the plasma can be obtained without interference from the source light. However, it should be understood that in some embodiments, the source light may be on during measurement of the process signal. Additionally, it should be understood that one or both of the reference signal and process signal may be obtained during processing of one or more substrates within the chamber. The measurements are therefore sometimes referred to as in situ measurements.

Referring now to FIG. 7, a block diagram of an exemplary computer system 760 of a processing tool is shown, according to one embodiment. In one embodiment, computer system 760 is coupled to and controls processing within the processing tool. Computer system 760 may be connected (eg, networked) to other machines over a local area network (LAN), an intranet, an extranet, or the Internet. Computer system 760 can operate as a server or client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system 760 may be implemented by a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), mobile phone, web appliance, server, network router, switch, or bridge, or any machine thereof. It can be any machine that can execute a set of instructions (sequential or otherwise) that specify an action to be taken. Additionally, although only a single machine is shown for computer system 760, the term "machine" also includes a set of instructions (or a set of instructions) for performing any one or more of the methodologies described herein. shall be construed to include a collection of machines (e.g., computers) that individually or jointly execute a plurality of sets).

Computer system 760 is a computer program product or software having a non-transitory machine-readable medium storing instructions that may be used to program computer system 760 (or other electronic device) to perform processes according to embodiments. 722. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (eg, a computer). For example, machine-readable (e.g., computer-readable) media includes machine-readable (e.g., computer)-readable storage media (e.g., read-only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage machine (e.g., computer) readable transmission media (e.g., electrical, optical, sound, or other forms of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.

In one embodiment, the computer system 760 includes a system processor 702, a main memory 704 (e.g., dynamic random access memory (DRAM), such as read only memory (ROM), flash memory, synchronous DRAM (SDRAM), or Rambus DRAM (RDMAM)). ), static memory 706 (eg, flash memory, static random access memory (SRAM), etc.), and secondary memory 718 (eg, a data storage device), which communicate with each other via bus 730.

System processor 702 represents one or more general purpose processing devices such as a microsystem processor, central processing unit, etc. More specifically, system processors include complex instruction set computing (CISC) microsystem processors, reduced instruction set computing (RISC) microsystem processors, very long instruction word (VLIW) microsystem processors, and other instruction set processors. It may be a system processor that implements a system processor or a system processor that implements a combination of instruction sets. System processor 702 may also be one or more special purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), a network system processor, etc. System processor 702 is configured to execute processing logic 726 to perform the steps described herein.

Computer system 760 may further include a system network interface device 708 for communicating with other devices or machines. Computer system 760 also includes a video display unit 710 (e.g., a liquid crystal display (LDC), light emitting diode display (LED), or cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), a cursor control device 714 (e.g., , a mouse), and a signal generating device 716 (eg, a speaker).

Secondary memory 718 includes machine-accessible storage in which one or more sets of instructions (e.g., software 722) that embody any one or more of the methodologies or functions described herein are stored. A medium 731 (or more specifically a computer readable storage medium) may be included. Software 722 may also reside entirely or at least partially within main memory 704 and/or within system processor 702 during its execution by computer system 760, with main memory 704 and system processor 702 also being machine readable. Configure storage media. Software 722 may further be transmitted or received over network 720 via system network interface device 708. In one embodiment, network interface device 708 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

Although machine-accessible storage medium 731 is shown to be a single medium in the exemplary embodiment, the term "machine-readable storage medium" refers to a single medium that stores one or more sets of instructions. or multiple media (e.g., centralized or distributed databases and/or associated caches and servers). The term "machine-readable storage medium" is also interpreted to include any medium capable of storing or encoding a set of instructions that are executed by a machine and cause the machine to perform any one or more of the methodologies. shall be taken as a thing. Accordingly, the term "machine-readable storage medium" should be construed to include, but not be limited to, solid state memory, and optical and magnetic media.

Certain exemplary embodiments have been described in the foregoing specification. It will be apparent that various modifications may be made without departing from the scope of the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Claims (15)

housing,
an optical path through the housing, the optical path including a first end and a second end;
a reflector at the first end of the optical path; and an opening through the housing between the second end of the optical path and the reflector;
An optical sensor system comprising: a light source optically coupled to the optical path; and a sensor optically coupled to the optical path.
The optical sensor system of claim 1, further comprising: 3. The optical sensor system of claim 2, wherein the light source is a single wavelength source. 3. The optical sensor system of claim 2, wherein the light source is a broadband light source. 3. The optical sensor system of claim 2, wherein the light source and the sensor are optically coupled to the optical path by a fiber optic cable. 6. The optical sensor system of claim 5, wherein the fiber optic cable comprises a splitter. 3. The optical sensor system of claim 2, further comprising a bandpass filter located along an optical path between the sensor and the aperture. 3. The optical sensor system of claim 2, wherein the sensor is a spectrometer or a photodiode. 3. The optical sensor system of claim 2, wherein the light source and the sensor are integrated into the housing. A method for measuring process conditions or chamber conditions within a processing chamber, the method comprising:
obtaining a reference signal;
obtaining a process signal; and comparing the process signal with the reference signal;
including;
Obtaining the reference signal comprises:
emitting electromagnetic radiation from a source outside the chamber, the electromagnetic radiation propagating along an optical path between the source and a reflector within the chamber;
reflecting the electromagnetic radiation along the optical path with the reflector; and sensing the reflected electromagnetic radiation with a sensor optically coupled to the optical path.
including;
Obtaining the process signal comprises:
sensing electromagnetic radiation emitted within the processing chamber and traveling along the optical path with the sensor;
including methods. 11. The method of claim 10, wherein the reference signal is obtained when no process is being performed in the chamber. 11. The method of claim 10, wherein the reference signal is obtained during processing within the chamber. An optical sensing array for a plasma processing chamber comprising:
a plurality of optical sensing systems oriented around the processing chamber, each of the plurality of optical sensing systems comprising:
housing,
an optical path through the housing, the optical path including a first end and a second end;
a reflector at the first end of the optical path; and an opening through the housing between the second end of the optical path and the reflector;
An optical sensing array comprising: 14. The optical sensing array of claim 13, wherein the plurality of optical sensing systems are configured to provide plasma condition, wall condition, or plasma condition and wall condition uniformity data. 14. The optical sensing array of claim 13, wherein the plurality of optical sensing systems are configured to provide chamber drift monitoring.

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